A REVISrON OF THE BRITISH IDOTEID^E. 741 



margins of the second to seventh segments, gradually increasing in width, smaller 

 in female. Maxillipedes (fig. 31) with four-jointed palp, groove on the third joint 

 very slight, basal plate elongated, with inner lobe fairly broad, epipodite extending 

 to the middle of the third joint of the palp. Thoracic appendages (figs. 32 and 33) 

 moderately strong. Metasome (fig. 35) with two short segments and sutural 

 indications of a third coalesced segment, terminal segment long, raised in the mid- 

 dorsal line, slightly narrowing distally, terminating in an obtuse point, lateral angles 

 rounded. Uropoda (fig. 36) broad, bluntly rounded anteriorly, with raised inner 

 margin, posterior margin obliquely excavate, endopodite terminally transversely 

 truncated. 



Length of c? 27 '5 mm., of P 16-17 mm. 



Colour dark brown or greenish-black, sometimes variegated with irregular 

 lighter-coloured patches. 



Geographical Distribution. — St Andrews Bay, Firth of Forth, Lowestoft, and 

 Plymouth ; Clyde Area (Patience) ; Moray Firth (Scott) ; Shetland and Falmouth 

 (Norman) ; west coast of Ireland (Tattersall) : also Norwegian coast (Norman and 

 Sars). 



(4) Idotea emarginata (Fabr.). (PI. VI, figs. 37-47.) 



Gymothou emarginata, Fabricius, Entom. Syst., 1793, vol. ii, p. 508. 



Holea emarginata, Fabricius, Entom. Syst. Supply 1798, p. 303; Latreille, Hist. Nat. Crud. et Ins., 1803, 



vol. vi, p. 370; Milne-Edwards, Hist. Nat. Crust., 1840, vol. iii, p. 130; Bate and Westwood, 



Brit. Sessile-eyed Crust., 1868, vol. ii, p. 386, figs.; Miers, Journ. Linn. Soc. Loud., 1881, vol. xvi, 



p. 43. 

 Idotea oestrum, Leach, Trans. Linn. Soc. Lond., 1815, vol. xi, p. 365; Desmarest, Consid. Crust., 1825, 



p. 289. 

 Idothea emarginata, G. O. Sars, Crust. Norw., 1897, vol. ii, p. 85, pi. xxxv, fig. 2. 

 Idotea emarginata, Dollfus, Feuille des jcuues Nat., 1895, p. 6, figs. 17, 18; Norman, Ann. and Mag. Nat. 



Hist., 1904 (s. 7), vol. xiv, p. 443; Tattersall, Nord. Plank., 1911, p. 226, figs. 111-115. 



Body oblong oval, slightly convex, surface smooth. Cephalon (fig. 37) wider 

 than long, anterior margin slightly emarginate, posteriorly with sinuous line. 

 Eyes large and • round, situated dorso-laterally. Antennulae (fig. 38) extending to 

 the end of the third peduncular joint of the antennae ; first joint much expanded 

 and produced on the inner side, second smaller, third elongated. Antennae (figs. 

 39 and 40) long, first three joints excavated on their outer side, fourth and fifth 

 elongated ; fiagellum composed of from fourteen to sixteen joints, with elongate 

 setose style. First maxillae (fig. 41) with outer lobe terminating in eight stout 

 curved spines and two toothed ones, inner lobe with three elongated setose spines, 

 rather wide at their bases, and with small setule distally at the outer border. The 

 segments of the mesosome (fig. 45) almost subequal, anterior angle of the pleural 

 plates of first segment sharply pointed. Coxal plates wide and occupying the 

 whole of the lateral margins of the second to seventh segments, posterior angle of 

 the seventh produced backwardly as sharp spine. Maxillipedes (fig. 42) elongated 



